Diamond Certification Companies: GIA vs IGI vs HRD

By Cameron Malakan, owner of Clairamor and third-generation jeweler · Updated September 24, 2026

For a lab-grown diamond bought today, three certification companies matter: IGI, GIA and HRD Antwerp. IGI grades most of the world's lab-grown diamonds and still issues full color, clarity and cut grades. GIA stopped putting D-to-Z color and clarity grades on lab-grown diamonds on October 1, 2025, and now issues a Quality Assessment that calls a stone Premium or Standard. HRD Antwerp grades lab-grown stones on the full scale, like IGI. Every diamond in Clairamor's picker carries a report from one of the three, with the report number laser-inscribed on the girdle and a link to the lab's own record. This guide compares the labs, explains what each line on a report means using a real report from our inventory, and shows how to verify any report in under a minute.

Loupe held over a round lab grown diamond, the way a grader inspects clarity at 10x magnification — A grading report records what a trained grader sees under 10x magnification, then a second grader checks it.

Diamond certification companies at a glance

Lab	Lab-grown report	Color and clarity grades?	Verify a report	At Clairamor
IGI International Gemological Institute, Antwerp, labs worldwide	Laboratory Grown Diamond Report	Yes, full D-to-Z and FL-to-I3 scales, plus cut grade on rounds	igi.org/verify-your-report	Most stones in our picker
GIA Gemological Institute of America, Carlsbad, California	Laboratory-Grown Diamond Quality Assessment (from October 1, 2025)	No longer. New reports say Premium or Standard; reports issued before September 30, 2025 carry full grades	gia.edu Report Check	Stocked
HRD Antwerp Belgium's diamond lab	Laboratory Grown Diamond Certificate	Yes, full scales	my.hrdantwerp.com	Stocked
GCAL Gem Certification and Assurance Lab, New York	Lab-grown diamond certificate with its own cut analysis	Yes, full scales	gcalusa.com	Not stocked; a sound report if you have one
AGS Laboratories	No new reports; closed in 2022 when its cut-grading work moved to GIA	Older reports use a 0-to-10 scale	Older reports only	Not stocked
EGL EGL USA and EGL International are separate businesses	Various	Yes, but with a long reputation for grading a step or two looser than the labs above	Varies by branch	Not stocked; price an EGL stone as if its grades were lower

What a diamond certification actually is

A diamond certification is a grading report: a document from an independent laboratory that identifies a specific stone and records what a trained grader measured and saw. It confirms the diamond is a diamond (and whether it was grown or mined), gives its weight and dimensions, and grades its color, clarity and finish against a published scale. What it is not is a valuation. A report never states a price, and it is not the same as an appraisal, which is a jeweler's written estimate of replacement value for insurance.

The word "certificate" survives from an older era, but the labs themselves call these documents reports, because grading is an expert opinion rather than a guarantee. The same stone sent to two labs can come back a grade apart in color or clarity, which is why the lab's name on the report matters as much as the grades on it. Every stone in Clairamor's picker is listed with its lab, its report number and a link to the lab's record, so you can check the grades before you check out.

The big change: GIA stopped grading lab-grown diamonds on the 4Cs

On June 2, 2025, GIA announced that it would stop describing lab-grown diamonds with the D-to-Z color scale and the Flawless-to-Included clarity scale, on the grounds that more than 95 percent of lab-grown stones fall into a narrow band at the top of both scales. Its chief laboratory officer, Tom Moses, said it was "no longer relevant" to use the nomenclature built for natural diamonds. The old GIA lab-grown reports were discontinued on September 30, 2025, and the replacement, the Laboratory-Grown Diamond Quality Assessment, launched on October 1, 2025.

The assessment still examines color, clarity, cut, polish and symmetry, but it reports one of two words instead of a set of grades. The thresholds are public, and they are strict:

	GIA Premium	GIA Standard	Below Standard
Color	D	E to J	No assessment is issued; GIA charges a small evaluation fee and returns the stone
Clarity	VVS2 or better	VS1 or VS2
Polish	Excellent	Very Good
Symmetry	Excellent	Very Good (Good for fancy shapes)
Cut (rounds only)	Excellent	Very Good

What this means when you shop: a new GIA assessment tells you which band a lab-grown stone sits in, not whether it is a D or an F, a VVS1 or a VS2. Premium is a narrow, excellent band, since D color and VVS2 clarity are the top of both scales. Standard is wide: it covers E through J, which runs from colorless to a visible warmth. If you care about the exact color or clarity of a stone, you want an IGI or HRD report, or a GIA report issued before the change. Clairamor's picker only lists stones in D to G color and IF to VS2 clarity, so a GIA-assessed stone in our inventory sits inside those limits whatever the assessment says.

GIA vs IGI vs HRD for lab-grown diamonds

The three labs in our picker agree on far more than they differ. All three examine the stone itself, not paperwork; all three confirm that it is laboratory-grown; and all three inscribe lab-grown stones with the report number as standard practice. The differences are in what they report and in reputation.

	IGI	GIA	HRD Antwerp
Grading lab-grown since	2005; the most widely used lab for lab-grown stones	Full reports until 2025, Quality Assessment since	Full reports; widely used in Europe
Color and clarity	Full grades	Premium or Standard	Full grades
Cut grade	Rounds graded; fancy shapes get polish and symmetry plus a four-step cut description	Rounds only, folded into Premium or Standard	Cut grade on rounds; polish and symmetry on every shape
Growth method and treatment	Stated (CVD or HPHT, and any post-growth treatment)	Identified as laboratory-grown; inscribed "Laboratory-Grown"	Stated
Plot and proportions	Proportions diagram; clarity plot on larger stones	No clarity plot on the Quality Assessment	Proportions; plot on larger stones
Reputation for strictness	Historically a touch softer than GIA on mined stones; the reference standard for lab-grown	The benchmark for mined diamonds	Close to GIA on mined stones
Inscription	"IGI LG" plus the report number	"Laboratory-Grown" plus the assessment number	Report number

Our house view, from the stones that cross our bench: for a lab-grown diamond, an IGI or HRD report gives you more usable information than a new GIA assessment, because it tells you the actual color and clarity. The old worry that IGI grades loosely comes from the mined-diamond market a decade ago. On lab-grown stones we see IGI, HRD and pre-2025 GIA reports land within a grade of each other, and because clarity moves lab-grown prices so little (our guides to VVS1 and SI clarity show why), a one-grade difference is rarely worth arguing about. What is worth insisting on is that the report exists, that it is from one of these labs, and that it matches the stone in front of you.

How to read a lab-grown diamond report, line by line

The table below walks through a real IGI report for a stone listed in Clairamor's picker while this guide was written: report LG781652039, issued March 12, 2026, for a 1.01 carat moval-outline stone. The same lines appear, in a slightly different order, on HRD and older GIA reports.

Line on the report	On report LG781652039	What it tells you
Report number and date	LG781652039, March 12, 2026	The number you type into the lab's website; "LG" marks it as a lab-grown report
Description	Laboratory Grown Diamond	The lab tested the stone and confirmed it is a diamond that was grown, not mined
Shape and cutting style	Oval Brilliant	The outline and faceting family. Trade names like moval or elongated cushion do not appear; judge those from the measurements
Measurements	7.64 x 5.32 x 3.39 mm	Length, width, depth. Length divided by width is the ratio (1.44 here); this is also how you match a report to a stone
Carat weight	1.01 carat	Weight to two decimals; 1.00 and 1.01 look identical, and price steps at the round numbers
Color grade	D	D, E and F are colorless; G to J near-colorless. Clairamor stocks D to G
Clarity grade	VS1	Inclusions seen under 10x. Anything VS2 or better is eye-clean in practice; we stock IF to VS2
Cut grade	Blank	Only round brilliants get a cut grade. For every other shape, read polish, symmetry and the proportions instead
Polish and symmetry	Very Good, Very Good	Surface finish and facet alignment. Excellent or Very Good is what you want; Good is acceptable on a fancy shape
Fluorescence	None	Glow under UV light. None to Faint is the norm on lab-grown stones and has no effect on how they look
Inscription	IGI LG781652039	Laser-etched on the girdle in letters too small to see without a loupe; the physical link between the stone and the report
Comments	Created by CVD growth process; Type IIa	CVD or HPHT is the growth method. Type IIa means no measurable nitrogen, which is typical of CVD stones. This is also where any post-growth treatment is disclosed
Proportions	Depth 63.7%, table 62%	Depth and table as a percentage of width. Our picker shows both for every stone; very deep stones look small for their weight
Plot	Not shown on this report	A diagram of where inclusions sit, usually on larger stones. Red marks are internal, green are surface; anything under the table deserves a look on the video

Two habits make reports useful rather than intimidating. Read the measurements before the grades, because size and shape are what you will actually see. And read the comments line, because that is where the lab tells you how the stone was grown and whether it was treated afterward. Our guide to the 4Cs goes deeper on each grade, and the lab-grown diamond buying guide puts them in order of what matters for the price.

How to verify a diamond report in under a minute

Find the report number. It is printed on the report and, at Clairamor, shown on every stone in the picker. IGI numbers on lab-grown stones start with LG.
Type it into the lab's own site. IGI Verify Your Report, GIA Report Check or HRD Antwerp's report search. Never verify through a link the seller provides; go to the lab directly.
Match the numbers, not just the name. Carat weight and the three measurements should match the listing exactly. A stone and a report that agree on "1.01 ct D VS1" but disagree on 7.64 x 5.32 x 3.39 mm are not the same stone.
Check the inscription. With a 10x loupe, find the report number on the girdle. Our team does this for every stone before it is set.
Ask for the PDF. The lab's record is the authority, but the original document is what your insurer and any future buyer will want with the appraisal.

Which diamond certification is best for a lab-grown diamond?

IGI, if you want the fullest information on the most stones. It grades color and clarity on the full scale, states the growth method and any treatment, and has graded lab-grown diamonds for two decades, so its reports are the ones most retailers, insurers and appraisers see every day. HRD Antwerp is equally sound and simply less common in the United States. GIA remains the most recognized name in diamonds, and a GIA assessment is a fine thing to have on a lab-grown stone, as long as you understand that Premium and Standard are bands rather than grades. Avoid stones with no independent report, stones whose only "certificate" is the seller's own letterhead, and reports from labs that grade loosely; you will pay for grades the stone does not have.

Where Clairamor fits

Every diamond in Clairamor's picker is lab-grown, D to G in color, IF to VS2 in clarity, and comes with an IGI, GIA or HRD report whose number is inscribed on the girdle and linked from the listing, alongside a 360 video and the stone's depth and table. We check the inscription against the report before a stone is set, and every ring ships with the report and an insurance appraisal.

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Frequently asked questions

What is the best diamond certification?

For mined diamonds, GIA is the benchmark. For lab-grown diamonds, IGI is the most widely used and still issues full color and clarity grades, which GIA no longer does; HRD Antwerp is a sound alternative. All three are independent laboratories that inscribe the report number on the stone.

Is IGI certification as good as GIA?

For lab-grown diamonds, yes, and in one respect better: an IGI report states the actual color and clarity grade, while a GIA Quality Assessment issued after October 1, 2025 only says Premium or Standard. IGI's reputation for grading a little more generously comes from the mined-diamond market and is not a reason to avoid it on a lab-grown stone.

Why did GIA stop grading lab-grown diamonds on the 4Cs?

GIA said in June 2025 that more than 95 percent of lab-grown diamonds fall into a narrow range of color and clarity, so the scales built for natural diamonds no longer describe them usefully. Its lab-grown reports with D-to-Z grades ended on September 30, 2025, replaced by the Premium or Standard Quality Assessment.

What does GIA Premium mean on a lab-grown diamond?

Premium means the stone graded D in color, VVS2 or better in clarity, Excellent in polish and symmetry, and, for a round, Excellent in cut. Standard covers E to J color, VS clarity and Very Good finish. A stone below Standard receives no assessment.

Is HRD a good diamond certification?

Yes. HRD Antwerp is Belgium's diamond laboratory and grades lab-grown diamonds on the full color and clarity scales, with the growth method stated. It is less common than IGI in the United States, which is the only reason its reports are seen less often.

How do I verify a diamond certificate?

Enter the report number on the lab's own website: IGI's Verify Your Report page, GIA's Report Check or HRD Antwerp's report search. Confirm the carat weight and millimeter measurements match the stone, then check the inscription on the girdle with a 10x loupe.

What is the difference between a diamond certificate and an appraisal?

A certificate, properly a grading report, is an independent lab's description of the stone: identity, weight, measurements and grades, with no price. An appraisal is a jeweler's written estimate of replacement value for insurance. You want both; Clairamor supplies both with every ring.

Does a lab-grown diamond need a certificate?

Any stone worth insuring should have one. The report confirms the stone is a laboratory-grown diamond rather than a simulant, records its grades from an independent grader, and gives you the inscribed number that ties the document to the stone for resale, insurance or repair.

What does "as grown" or "post-growth treatment" mean on a report?

Some lab-grown diamonds are heated or pressure-treated after growth to improve their color. Labs disclose this in the comments line. "As grown" means no treatment was detected. Treatment is permanent and common, but a stone that needed it started out with more color, so the note is worth reading.

Are EGL diamond certificates reliable?

EGL is a group of separately owned labs with a long reputation for grading more generously than GIA, IGI or HRD. An EGL report is not worthless, but the safe approach is to price the stone as if its color and clarity were a grade or two lower, or to have it regraded. Clairamor does not stock EGL-graded stones.